Rheology of dense suspensions of non colloidal particles

Élisabeth Guazzelli

doi:10.1051/epjconf/201714001001

Abstract

Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers) or non-Newtonian fluids that we will also address.

Highlights

Dense suspensions are materials with broad applications both in industrial processes and in natural phenomena
The fundamental problem is to determine the rheological properties of these media from a knowledge of the mechanics of the particles and the interstitial fluid
The major difficulty of dense particulate flows is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact

Summary

Introduction

Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). The fundamental problem is to determine the rheological properties of these media (considered as equivalent homogeneous materials) from a knowledge of the mechanics of the particles and the interstitial fluid. The major difficulty of dense particulate flows is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. Dense or highly concentrated particulate flows belong to an intermediate regime between pure suspensions and granular flows. The complex nature of these particle interactions greatly contribute to the lack of understanding of these systems. The present contribution aims at providing a review of recent work on the rheology of dense suspensions of non colloidal particles. These studies were done in collaboration with F.

Suspension viscosity

Non-Newtonian behavior

Irreversible dynamics

A frictional approach

Toward more complex particulate systems